Marine essential fatty acids are provided by fish, algae, and the tiny shrimp known as krill. Supplements made from krill oil are advertised as "superior to fish oil in every way" and "offering unparalleled support of cardiovascular and women's health," but the advertisements don't tell the whole story.
What Are Krill?
Krill are tiny shrimp-like crustaceans that live near icebergs. They are easy to distinguish from true shrimp by their visible outside gills. Most adult krill grow to just 1 to 2 cm (0.4 to 0.8 inches) in length, making them a tasty bite for walruses, penguins, and larger sea creatures. A few krill can grow to the size of small shrimp. Most of the body is high in fluorides and toxic, but the tail meat is edible. It is made into okiami for the Japanese market and a minced, pink "mystery food" that was once sold in the Soviet Union. Krill travel up and down the edge of icebergs every day in search of the even smaller marine plants on which they feed. They use feces as ballast. They feed and accumulate feces as they go down the side of the iceberg, and when they defecate, they come back to the surface to start their feeding cycle all over again.
What Is Krill Oil?
Krill can be caught in nets when they surface, along with all kinds of other sea creatures, since the mesh of the net has to be relatively small. Krill can then be ground up and steamed to release the oil in their tail meat. This is the only practical way to process these tiny sea creatures, since there is no way to eat a krill tail that is just 0.1 inch/2 mm long!
So, Is Krill a Superior Product? Any Krill Oil Side Effects?
The claims that krill oil is superior to fish oil rest on two alleged properties of krill. One claim made for krill is that they contain more antioxidants than fish. The other claim made for krill is that they are less likely to go bad than fish. The second claim is obviously true. Just as fluoride in drinking water helps preserve your teeth, fluoride in krill shells helps preserve krill. It also makes most of the animal toxic to humans, but it definitely fights decay.
The first claim, however, is open to interpretation. Antioxidants help keep people "fresh." Antioxidants also keep fish oil and krill oil fresh. It's the process of storing the catch in the ship's hold and the temperatures at which the products are processed that make the difference in how many antioxidants are in the finished product.
If you are comparing krill caught off Antarctica and mahi-mahi caught off Maui, both kept on the boat for a month, yes, krill indeed would be fresher and also richer in antioxidants. But for fish oil, the measure of antioxidant power is the presence of trimethylamine oxide (TMAO), trimethyl amine (TMA), and total volatile basic nitrogen (TVN). Products that are made in ways that stop these markers of rancidity are just as fresh and just as full of antioxidants. (More about krill oil versus fish oil)
If Krill Oil Is As Good as Fish Oil, Why Not Buy It?
The fact is, carefully processed krill oil probably is just as good for you as fish oil—if you don't mind depriving a penguin and her chick of their lunch. But if the product costs five times as much to deliver the same amount of DHA and EPA, perhaps fish oil is a better choice.